1. Field of the Invention
The invention relates generally to a storage apparatus and a volume restoration method, and is suitable for use in, for example, a data restoration method based on storage apparatus CDP (Continuous Data Protection) processing in the storage apparatus.
2. Description of Related Art
CDP is a technique of restoring a volume in a storage apparatus. CDP is a technique in which a host connected to a storage apparatus is not used, writing to a volume targeted for data protection is stored as update history only in the storage apparatus, and an image from a given past point in time can be restored. In CDP, a user sets an arbitrary protection period in advance, thereby enabling restoration of an image from an arbitrary point in time within the range of the protection period. The arbitrary point in time can be specified by a user by time specification, marker specification, etc.
A known technique of acquiring a snapshot in a volume from a certain point in time is known (see, e.g., JP2004-342050 A).
In performing CDP, a storage apparatus stores all write data. As a result, write data is stored even during a time period in which data restoration is unnecessary. Accordingly, there has been a problem in that storing unnecessary write data leads to enormous amounts of data in a volume, and enormous amounts of data invite a longer volume restoration time.
There are other data copy techniques, including a remote copy technique for conducting data copy between plural storage apparatuses, a local copy technique for conducting data copy between plural volumes in a single storage apparatus, and a snapshot technique for preserving data at a certain point in time. In the remote copy and local copy techniques, a volume can be restored to its most recent state, but not to a past state. Also, in the snapshot technique, if the time is specified in advance, a volume can be restored to its state as of at that specified point in time, but not to its state as of at an arbitrary point in time.